Thermal right, land left

In article ,
Eric Greenwell wrote:
Mark James Boyd wrote:
It might be useful to look at small airplane accidents, since they DO
have stall warning horns. I'm under the impression that stall/spin
accidents are a big cause of fatal accidents also. Do you have any numbers?


I looked up the last ten years of gliders (49 fatalities)
and then I looked up a three month window of airplane fatalities
from 3/94 to 6/94 (102 fatalities). I got lazy and didn't want
to look through more than 100, but I wanted to see final reports, so...

Gliders: 21 stalls of 49 fatalities = 43%

If you eliminate midairs and disconnected controls, 21 of 42 = 50%

Airplanes: 9 stalls of 102 fatalities = 9%

If you eliminate midairs and disconnected controls, 9 of 91 = 10%

A bunch of the airplane ones were also night and/or IFR (less than
half). But it seemed real clear that more of the glider fatalities
could have been stalls. Anyway, I concluded that airplane guys
don't stall very much close to the ground...

I was also VERY surprised to find a lot of medical problems
with airplenes, and I don't think even one fatal glider accident
due to a medical condition. This is really surprising...I'll
need to look at all 250 fatal glider reports at some point to
see if there are ANY medical fatalities...

Anyway, yes glider pilots die from stalls as a real big
factor. I think it's because they don't have warning devices.
Hells bells, just hook 'em to the gear down and spoiler cracked
switches, so they're off the rest of the time (thermalling).

Or maybe somebody has a better idea. I dunno, I'm just real
surprised we don't have any stall horns at all on any gliders...

I'm not suggesting this isn't a good idea, but I do wonder...

Why do airplanes have ANY stall/spins during landing? Typically, they
have full control of their pattern (altitude, entry point), while the
glider accidents most often occur when the pilot can't do the desired
pattern because he returns too low.

Maybe we don't need a stall warning for gliders: perhaps a simple
airspeed alert would do everything that is needed, as long as it was
enabled by the gear being extended. I think it should alert regardless
of the spoiler position, since a low, slow pilot isn't likely to open
the spoilers.

DG sailplanes makes such a device, called the DSI. Take a look he

http://www.dg-flugzeugbau.de/dsi-e.html
DG Flugzeugbau GmbH / DSI - Digital Soaring Indicator

Is anyone using one of these? Maybe we already have what we need, but
not enough people are using it.

Well, some of the power accidents are just newer pilots that
weren't trained to properly react to the horn. In some
I suspect the horn wasn't even working (I've been surprised by
failed horn a few times).

The airspeed idea is good (better than nothing) but doesn't
tell the AOA at both wingtips, and doesn't seem to account for the
G loading in a tight turn. Also, as another poster pointed out,
the horn detects gusts, which is pretty useful IMHO.

In any case, I'd just love to have a glider with an AOA tab
(each with a different tone) on each wingtip, and teach some spins in it.
I'd also love to see how well it does when thermalling. Maybe
Andreas is right and one can't tell horn vs. vario, but it would be
a kick to try...

Anyway, just another fun idea...now let's cut out this
nonsense and get back to implementing the turbine powered sparrowhawk ;P

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Mark Boyd
Avenal, California, USA